/* ****************************************************************************
 *
 * Copyright (c) Microsoft Corporation. 
 *
 * This source code is subject to terms and conditions of the Apache License, Version 2.0. A 
 * copy of the license can be found in the License.html file at the root of this distribution. If 
 * you cannot locate the  Apache License, Version 2.0, please send an email to 
 * dlr@microsoft.com. By using this source code in any fashion, you are agreeing to be bound 
 * by the terms of the Apache License, Version 2.0.
 *
 * You must not remove this notice, or any other, from this software.
 *
 *
 * ***************************************************************************/

using System;
using System.Diagnostics;
using System.Dynamic.Utils;

#if SILVERLIGHT
using System.Core;
#endif

#if CLR2
namespace Microsoft.Scripting.Ast {
#else
namespace System.Linq.Expressions {
#endif
    /// <summary>
    /// Emits or clears a sequence point for debug information.
    /// 
    /// This allows the debugger to highlight the correct source code when
    /// debugging.
    /// </summary>
#if !SILVERLIGHT
    [DebuggerTypeProxy(typeof(Expression.DebugInfoExpressionProxy))]
#endif
    public class DebugInfoExpression : Expression {

        private readonly SymbolDocumentInfo _document;

        internal DebugInfoExpression(SymbolDocumentInfo document) {
            _document = document;
        }

        /// <summary>
        /// Gets the static type of the expression that this <see cref="Expression" /> represents. (Inherited from <see cref="Expression"/>.)
        /// </summary>
        /// <returns>The <see cref="Type"/> that represents the static type of the expression.</returns>
        public sealed override Type Type {
            get { return typeof(void); }
        }

        /// <summary>
        /// Returns the node type of this <see cref="Expression" />. (Inherited from <see cref="Expression" />.)
        /// </summary>
        /// <returns>The <see cref="ExpressionType"/> that represents this expression.</returns>
        public sealed override ExpressionType NodeType {
            get { return ExpressionType.DebugInfo; }
        }

        /// <summary>
        /// Gets the start line of this <see cref="DebugInfoExpression" />.
        /// </summary>
        public virtual int StartLine {
            get { throw ContractUtils.Unreachable; }
        }

        /// <summary>
        /// Gets the start column of this <see cref="DebugInfoExpression" />.
        /// </summary>
        public virtual int StartColumn {
            get { throw ContractUtils.Unreachable; }
        }

        /// <summary>
        /// Gets the end line of this <see cref="DebugInfoExpression" />.
        /// </summary>
        public virtual int EndLine {
            get { throw ContractUtils.Unreachable; }
        }

        /// <summary>
        /// Gets the end column of this <see cref="DebugInfoExpression" />.
        /// </summary>
        public virtual int EndColumn {
            get { throw ContractUtils.Unreachable; }
        }

        /// <summary>
        /// Gets the <see cref="SymbolDocumentInfo"/> that represents the source file.
        /// </summary>
        public SymbolDocumentInfo Document {
            get { return _document; }
        }

        /// <summary>
        /// Gets the value to indicate if the <see cref="DebugInfoExpression"/> is for clearing a sequence point.
        /// </summary>
        public virtual bool IsClear {
            get { throw ContractUtils.Unreachable; }
        }

        /// <summary>
        /// Dispatches to the specific visit method for this node type.
        /// </summary>
        protected internal override Expression Accept(ExpressionVisitor visitor) {
            return visitor.VisitDebugInfo(this);
        }
    }

    #region Specialized subclasses

    internal sealed class SpanDebugInfoExpression : DebugInfoExpression {
        private readonly int _startLine, _startColumn, _endLine, _endColumn;

        internal SpanDebugInfoExpression(SymbolDocumentInfo document, int startLine, int startColumn, int endLine, int endColumn)
            : base(document) {
            _startLine = startLine;
            _startColumn = startColumn;
            _endLine = endLine;
            _endColumn = endColumn;
        }

        public override int StartLine {
            get {
                return _startLine;
            }
        }

        public override int StartColumn {
            get {
                return _startColumn;
            }
        }

        public override int EndLine {
            get {
                return _endLine;
            }
        }

        public override int EndColumn {
            get {
                return _endColumn;
            }
        }

        public override bool IsClear {
            get {
                return false;
            }
        }

        protected internal override Expression Accept(ExpressionVisitor visitor) {
            return visitor.VisitDebugInfo(this);
        }
    }

    internal sealed class ClearDebugInfoExpression : DebugInfoExpression {
        internal ClearDebugInfoExpression(SymbolDocumentInfo document)
            : base(document) {
        }

        public override bool IsClear {
            get {
                return true;
            }
        }

        public override int StartLine {
            get {
                return 0xfeefee;
            }
        }

        public override int StartColumn {
            get {
                return 0;
            }
        }

        public override int EndLine {
            get {
                return 0xfeefee;
            }
        }

        public override int EndColumn {
            get {
                return 0;
            }
        }
    }
    #endregion

    public partial class Expression {
        /// <summary>
        /// Creates a <see cref="DebugInfoExpression"/> with the specified span.
        /// </summary>
        /// <param name="document">The <see cref="SymbolDocumentInfo"/> that represents the source file.</param>
        /// <param name="startLine">The start line of this <see cref="DebugInfoExpression" />. Must be greater than 0.</param>
        /// <param name="startColumn">The start column of this <see cref="DebugInfoExpression" />. Must be greater than 0.</param>
        /// <param name="endLine">The end line of this <see cref="DebugInfoExpression" />. Must be greater or equal than the start line.</param>
        /// <param name="endColumn">The end column of this <see cref="DebugInfoExpression" />. If the end line is the same as the start line, it must be greater or equal than the start column. In any case, must be greater than 0.</param>
        /// <returns>An instance of <see cref="DebugInfoExpression"/>.</returns>
        public static DebugInfoExpression DebugInfo(SymbolDocumentInfo document, int startLine, int startColumn, int endLine, int endColumn) {
            ContractUtils.RequiresNotNull(document, "document");
            if (startLine == 0xfeefee && startColumn == 0 && endLine == 0xfeefee && endColumn == 0) {
                return new ClearDebugInfoExpression(document);
            }

            ValidateSpan(startLine, startColumn, endLine, endColumn);
            return new SpanDebugInfoExpression(document, startLine, startColumn, endLine, endColumn);
        }

        /// <summary>
        /// Creates a <see cref="DebugInfoExpression"/> for clearing a sequence point.
        /// </summary>
        /// <param name="document">The <see cref="SymbolDocumentInfo"/> that represents the source file.</param>
        /// <returns>An instance of <see cref="DebugInfoExpression"/> for clearning a sequence point.</returns>
        public static DebugInfoExpression ClearDebugInfo(SymbolDocumentInfo document) {
            ContractUtils.RequiresNotNull(document, "document");

            return new ClearDebugInfoExpression(document);
        }

        private static void ValidateSpan(int startLine, int startColumn, int endLine, int endColumn) {
            if (startLine < 1) {
                throw Error.OutOfRange("startLine", 1);
            }
            if (startColumn < 1) {
                throw Error.OutOfRange("startColumn", 1);
            }
            if (endLine < 1) {
                throw Error.OutOfRange("endLine", 1);
            }
            if (endColumn < 1) {
                throw Error.OutOfRange("endColumn", 1);
            }
            if (startLine > endLine) {
                throw Error.StartEndMustBeOrdered();
            }
            if (startLine == endLine && startColumn > endColumn) {
                throw Error.StartEndMustBeOrdered();
            }
        }
    }
}
